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C CLINICAL RESEARCH

Episodes of hypoglycemia may cause injury if they occur while a patient is driving or engaged in other poten-
tially dangerous activities. Over the long term, some studies have shown that frequent episodes of hypogly-
cemia (five or more since diagnosis) may be associated with a mild decrease in intellectual performance. 5,6,7
Patients with type 2 diabetes who have experienced severe hypoglycemia requiring a visit to the hospital may
also be at a greater risk of developing dementia in later years. After experiencing hypoglycemia, some patients
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may self-adjust their treatment in an attempt to prevent a future episode, potentially leading to worse overall
glycemic control. 9,10,11

Symptoms of hypoglycemia can usually be relieved by the ingestion of 15 grams of glucose (monosaccharide), which
will produce an increase in blood glucose of approximately 2.1 mmol/L within 20 minutes. Although many patients
with previous episodes of hypoglycemia carry an ‘emergency’ supply of carbohydrates with them, it would be pru-
dent for optometry offices to have at least one of the following items on hand at all times to support patients who
experience an in-office episode of hypoglycemia: 1

• 15 g glucose in the form of glucose tablets

• 15 mL (3 teaspoons) or 3 packets of table sugar to dissolve in water

• 175 mL (3/4 cup) of juice or regular soft drink
• 6 LifeSavers (1 = 2.5 g carbohydrate)

• 15 mL (1 tablespoon) of honey

Hyperglycemic crisis is a medical emergency that should be suspected and investigated in unwell patients with
diabetes. It is characterized by DKA and hyperosmolar hyperglycemic state (HHS), and requires immediate treat-
ment and monitoring for metabolic abnormalities and systemic complications.
Under insulin deficiency, hyperglycemia causes the urinary loss of water and electrolytes (sodium, potassium, chlo-
ride), resulting in depletion of the extracellular fluid volume (ECFV). Whereas DKA occurs as a result of elevated
glycation levels and absolute insulin deficiency in the case of type 1 diabetes, high catecholamine levels that sup-
press insulin release are implicated in the case of type 2 diabetes.

Symptoms of hyperglycemia include Kussmaul (deep laboured) respiration, acetone-odoured breath (beware mis-
interpretation as alcohol consumption), loss of extracellular fluid volume, nausea, vomiting and abdominal pain. As
with hypoglycemia, there may also be a decreased level of consciousness.

Patients with DKA or HHS are best managed in a hospital setting. Treatment is directed toward the restoration of
normal ECFV and tissue perfusion, resolution of ketoacidosis, and correction of electrolyte imbalances and hyper-
glycemia. The existence of concurrent illness should be investigated and treated as required.
CRITERIA FOR DIAGNOSIS
Canadian Diabetes Association (Diabetes Canada) Clinical Practice Guidelines (CPG) list the diagnostic criteria for
diabetes as follows: 12

• Fasting Plasma Glucose (FPG) ≥7.0 mmol/L (where fasting is defined as no caloric
intake for at least 8 hours);

• A1c ≥6.5% (in adults, using a standardized, validated assay in the absence of factors
that affect the accuracy of A1c (see below));

• 2-hour Plasma Glucose (PG) in a 75 g Oral Glucose Tolerance Test (OGTT) ≥11.1 mmol/L;

• Random PG ≥11.1 mmol/L (where random is defined as any time of the day,
without regard to the interval since the last meal).

8 CANADIAN JOURNAL of OPTOMETRY | REVUE CANADIENNE D’OPTOMÉTRIE VOL. 79 SUPPLEMENT 2, 2017